Magnetic Remanence of Stainless Steel and Titanium Alloy Orthopaedic Implants

Stainless steel and titanium alloys are common materials for orthopaedic implants. However there is a lack of information and studies on magnetic remanence of implants used in clinical practice. The aims of this study are to investigate the composition and the presence of magnetic remanence for these two orthopaedic implant materials. These two factors may cause implant instability and heat problems as well as degradation of the images quality if the patients undergo magnetic resonance imaging (MRI) examination. The magnetic hysteresis loop and remanence status of stainless steel and titanium alloy orthopaedic implants were investigated with a vibrating sample magnetometer (VSM). Both samples of stainless steel and titanium alloy had been exposed to external magnetic fields up to 1 T (10000 G) and 1.4 T (14000 G), respectively. The compositions of these two orthopaedic implant materials were studied using a scanning electron microscope with energy dispersive X-ray analysis (SEM-EDX). The results of the study demonstrated that ferrous and nickel compositions in stainless steel alloy orthopaedic implants contributed to the residual magnetism, as shown in the hysteresis loop. The titanium alloy orthopaedic implant sample does not contain any ferromagnetic elements. After exposure to a magnetic field, the stainless steel values of retentivity, coercivity and magnetisation are significantly higher compared to those of the titanium alloy. The stainless steel orthopaedic implant sample demonstrates a typical hysteresis loop that suggests the existence of magnetic remanence. In contrast, the titanium alloy orthopaedic implant sample showed no significant remanence phenomenon. By considering the existence of magnetic remanence in the implant is important as potential effect on the MRI image quality.

Improvements to the Shaw-Type Absolute Palaeointensity Method

Palaeointensity information enables us to define the strength of Earth’s magnetic field over geological time, providing a window into Earth’s deep interior. The difficulties in acquiring reliable measurements are substantial, particularly from older rocks. Two of the most significant causes of experimental failure are laboratory induced alteration of the magnetic remanence carriers and effects relating to multidomain magnetic carriers. One method that has been claimed to overcome both of these problems is the Shaw method. Here we detail and evaluate the method, comparing various selection criteria in a controlled experiment performed on a large, non-ideal dataset of mainly Precambrian rocks. Monte Carlo analyses are used to determine an optimal set of selection criteria; the end result is a new, improved experimental protocol that lends itself very well to the automated Rapid 2G magnetometer system enabling experiments to be carried out expeditiously and with greater accuracy.

Novel Polyimide/Copper-Nickel Ferrite Composites with Tunable Magnetic and Dielectric Properties

Heat-resistant magnetic polymer composites were prepared by incorporating cerium-doped copper-nickel ferrite particles, having the general formula Ni1-xCuxFe1.92Ce0.08O4 (x: 0.0, 0.3, 0.6, 1.0), into a polyimide matrix. The effects of particle type and concentration on the thermal, magnetic, and electrical properties of the resulting composites were investigated. The samples were characterized by FTIR, scanning electron microscopy, X-ray diffractometry, thermogravimetric analysis, differential scanning calorimetry, vibrating sample magnetometer, and broadband dielectric spectroscopy. The composites exhibited high thermal stability, having initial decomposition temperatures between 495 and 509 °C. Saturation magnetization (Ms), magnetic remanence (Mr), and coercivity (Hc) were found in range of 2.37–10.90 emu g−1, 0.45–2.84 emu g−1, and 32–244 Oe, respectively. The study of dielectric properties revealed dielectric constant values of 3.0–4.3 and low dielectric losses of 0.016–0.197 at room temperature and a frequency of 1 Hz.

Spheroid Nickel Nanoparticles Synthesized in CTAB Solution Using Gamma Radiation

Pure nickel nanoparticles with some paired grain shaped has been successfully synthesized using gamma radiation technique in aqueous system at ambient temperature without using reducing agent. Cetyl trimethylammonium bromide was used to prevent oxidation during radiolysis process and help to shape the nickel nanoparticles into spheroid. Synthesized nanoparticles were characterized using X-ray diffraction, tunnelling electron microscopy and vibrating sample magnetometer. The particles formed are crystallized with fcc phase without any oxidation state. The particle size ranging from 20 – 50 nm which consists of unique morphology of paired spheroid. Vibrating sample magnetometer analysis shows that sample has ferromagnetic properties with value of magnetic remanence smaller that bulk due to its size.

Nano-structural effects on Hematite (α-Fe2O3) nanoparticle radiofrequency heating

Nano-sized hematite (α-Fe2O3) is not well suited for magnetic heating via an alternating magnetic field (AMF) because it is not superparamagnetic—at its best, it is weakly ferromagnetic. However, manipulating the magnetic properties of nano-sized hematite (i.e., magnetic saturation (Ms), magnetic remanence (Mr), and coercivity (Hc)) can make them useful for nanomedicine (i.e., magnetic hyperthermia) and nanoelectronics (i.e., data storage). Herein we study the effects of size, shape, and crystallinity on hematite nanoparticles to experimentally determine the most crucial variable leading to enhancing the radio frequency (RF) heating properties. We present the synthesis, characterization, and magnetic behavior to determine the structure–property relationship between hematite nano-magnetism and RF heating. Increasing particle shape anisotropy had the largest effect on the specific adsorption rate (SAR) producing SAR values more than 6 × greater than the nanospheres (i.e., 45.6 ± 3 W/g of α-Fe2O3 nanorods vs. 6.89 W/g of α-Fe2O3 nanospheres), indicating α-Fe2O3 nanorods can be useful for magnetic hyperthermia.

Classifying Copper-Molybdenum-Gold Porphyry Deposit Alteration using Magnetic and Spectral data

<p>Copper is one of the most important critical metal resources needed to achieve carbon neutrality with a projected increase in demand of >300% over the next half century from electronics and renewables.  Porphyry deposits account for most of the global copper production, but the discovery of new reserves is ever more challenging. Machine learning presents an opportunity to cross reference new and traditionally under-utilised data sets with a view to developing quantitative predictive models of hydrothermal alteration zones to guide new, ambitious exploration programs.</p><p>The aim of this study is to demonstrate a new alteration classification scheme driven by quantitative magnetic and spectral data to feed a machine learning algorithm. The benefits of an alteration model based on quantitative data rather than subjective observations by geologists, are that there is no bias in the data collected, the arising model is quantifiable and therefore easy to model and the process be fully automated. Ultimately, this approach aids more detailed exploration and mine modelling, in turn, reducing the extraction process carbon footprint and more effectively identifying new deposits.</p><p>Presented here are magnetic susceptibility and shortwave infrared (SWIR) data collected from the KazMinerals plc. owned Aktogay Cu-Mo giant porphyry deposit, eastern Kazakhstan, which has a throughput of 30Mtpa of ore. These data are cross referenced using a newly developed machine learning algorithm. Generated autonomously, our results reveal twelve statistically and geologically significant clusters that define a new alteration classification for porphyry style mineralisation. Results are entirely non-subjective, reproducible, quantitative and modellable.</p><p>Importantly, magnetic susceptibility measurements improve the algorithm’s ability to identify clusters by between 29-36%; enhancing the sophistication of the included magnetic data promises to yield substantially better statistical results. Magnetic remanence data are therefore being complied on representative samples from each of the twelve identified clusters, including hysteresis, isothermal remanent magnetisation (IRM) acquisition, FORC measurements, natural remanent magnetisation (NRM) and anhysteretic remanent magnetisation (ARM). Through collaboration with industry partners, we aim to develop an automated means of collecting these magnetic remanence data to accompany the machine learning algorithm.</p>

Material, Magnetic, and Microbial Features of a Submarine Inflow ZoneTraversed by SUSTAIN Drill Cores, Surtsey Volcano, Iceland

<p>A series of basaltic eruptions from 1963 to 1967 off the southern coast of Iceland produced the oceanic island of Surtsey. Investigations of this volcanic system provide a time-lapse window into the real-time alteration of basaltic tephra through interactions with meteoric water in a subaerial tuff cone and with seawater in submarine deposits. In 1979, a 181 m core was recovered from a borehole (SE-01) on the eastern flank of the Surtur vent. In 2017, the ICDP-supported SUSTAIN drilling project drilled two vertical cored boreholes (SE-02a, SE-02b) to 151 and 187 m below surface (m b.s.) parallel to the 1979 borehole, and an additional angled cored borehole (SE-03) to 354 measured depth. These newly recovered cores, in comparison with the 1979 core, have promoted research into alteration processes within the volcano over the half century since its eruption. The scientific drilling undertaken in both 1979 and 2017 provides data critical to investigating mechanisms and rates of mineralogical change in basalt, evolving material and magnetic properties, and the characterization of basalt-hosted microbial communities.</p><p>            Previous research, including mineralogical analyses and geophysical downhole logging, reveals a weakly altered region at ~143-155 m b.s. that corresponds with a submarine zone of cool seawater inflow.  The purpose of this study is to better understand processes in this zone by examining SE-02b drill core samples taken at 141.6 m b.s. (83-86 °C) with mineralogical analyses and at 148 m b.s. (83-84 °C) with magnetic analyses and microbial community analyses. Mapping of the weakly-consolidated basaltic tuff at micrometer-scale using synchrotron X-ray micro-diffraction and micro-fluorescence studies shows that the basalt is primarily composed of fresh sideromelane glass, volcanic crystals, and open voids. Olivine and labradorite are the principal volcanic minerals; they have begun to alter to lizardite and aluminous tobermorite, respectively. The basaltic glass has begun to alter to nanocrystalline clinochlore and smectitic clay mineral, mainly nontronite and montmorillonite. The abundance of fresh glass, however, confirms a weakly altered region of the volcano. Uniaxial and cubic single domain titanomagnetite is the principal magnetic remanence carrier in the glass, whereas the magnetic minerals in more highly altered zones of lapilli tuff, only a few meters distant, are more oxidized and exhibit different magnetic anisotropies, consistent with the growth of secondary titanomaghemite. The properties of magnetic remanence remained relatively stable in the cool seawater inflow zone but changed very rapidly during fluid-rock interactions at higher hydrothermal temperatures. The microbial community detected in the drill core sample at 148 m b.s. from SE-02b is dominated by taxa generally found in seawater such as Psychromonas, Glaciecola, Marinomonas and suggests a possible infiltration of microbial taxa from the seawater to the submarine deposit. This anomalously permeable, poorly-consolidated horizon provides a strong contrast to the characteristics of the well-lithified lapilli tuff deposits and demonstrates the potential for substantial variability in mineralogical, magnetic and microbial submarine processes in other Surtseyan volcanoes and seamount structures.</p>